Poster Presentation 2-16

Functional Expression of Cellobiohydrolases in Saccharomyces cerevisiae

John McBride^1,2*, Danie C. La Grange², Ronel van Roven², J. J. Zeitsman², W. H. van Zyl² and L.R. Lynd^1,2

¹Thayer School of Engineering

Dartmouth College

Hanover, NH USA 03755

Phone: (603)646-3496

Fax: (603)646-3856

E-mail: John.E.McBride@Dartmouth.edu

²Department of Microbiology

University of Stellenbosch, South Africa

Cellobiohydrolase (CBH) is the major enzymatic activity associated with cellulose solubilization in non-complexed cellulase systems examined to date. Expression of CBH in Saccharomyces cerevisiae is of interest in the context of creating strains that combine the merits of yeast as an industrial microorganism with the ability to convert cellulose to products of interest without added saccharolytic enzymes. As a preliminary step in this direction, we report functional expression in S. cerevisiae Y294 of CBH1 from Trichoderma reesei, CBH1-4 from Phanaerochete chrysisporium, CBH2 from Trichoderma reesei, and CBHB from Aspergillus niger. The activity of these enzymes was assayed on cellulosic substrates (amorphous cellulose, and bacterial microcrystalline cellulose), and the mass concentrations of secreted CBH1 and CBH1-4 proteins were quantified using ELISA. Specific activities of the recombinant enzymes were determined based on either protein following affinity digestion purification or by ELISA. Current expression levels are evaluated in the context of requirements for growth on cellulose.